First, I have to credit Paul for clearly documenting the process for setting up Java 1.5 support for Opera 9 in this post on the Yellow Dog Community Board. The process for setting up Java 1.6 support is only slightly different.
To get Opera 9 installed, just browse to the Opera download page and select Yellow Dog under Select distribution and vendor. At the time I’m writing this it displays a version for Yellow Dog Linux 5.0 - 5.0.1, 5.0.2 (Sony Playstation 3 and Apple G4 - G5), but this works on Yellow Dog 6 as well. When the download starts you can just select Open with Software Installer. When installation is complete, Opera should show up in your menu under Applications -> Internet, or you can start it from the command line simply by entering opera.
If you have bookmarks from Firefox that you wish to import, start Opera and go to the menu item File -> Import and Export -> Import Netscape/Firefox bookmarks … This brings up a window labeled Select Netscape bookmarks to import. In the box next to Look in, you’ll need to enter ~/.mozilla to bring up the hidden folder in your home directory where the Firefox bookmarks are stored. Then double-click on the firefox folder, double-click the next folder that comes up (a random name ending in .default), and finally select bookmarks.html. Click on Open and a window should pop up letting you know how many were imported. These will be located under Bookmarks -> Opera -> Netscape bookmarks, but you can reorganize them later with Bookmarks -> Manage bookmarks.
If you’re unfamiliar with Opera, you can read about the various features by selecting Help -> Opera Help, or simply press the F1 key.
And now for the Java 1.6 support — first you need to have IBM Java 1.6 installed as described in this Howto (skipping the Mozilla plugin part if you want). Once you have IBM Java 1.6 installed you need to open a terminal window and create a symbolic link with this command (as root using su, or use sudo):
su [root password] ln -s /opt/ibm/java-ppc-60/jre/lib /opt/ibm/java-ppc-60/jre/lib exit
I realize this is creating a symbolic link to the /opt/ibm/java-ppc-60/jre/lib folder within the /opt/ibm/java-ppc-60/jre/lib folder, but that is what works. Otherwise Opera won’t recognize it as a valid path in the next step.
Back in Opera, go to the Tools -> Preferences menu and select the Advanced tab. Select Content from the list on the left side. and click the Java options… button. This will open a small window labeled Java. The box for Java path should be empty at this point. Click on Choose… and browse to the /opt/ibm/java-ppc-60/jre/lib/ppc/ folder, then click OK.
Note: If you copy/paste /opt/ibm/java-ppc-60/jre/lib/ppc/ into the Java path box instead, you still need to click on Choose… and OK or it doesn’t work properly in my experience with it.
Now click the Validate Java path button and it should say: The Java path seems to specify a valid directory. Your screen should look something like this:
Click OK to close the Validate Java path window, and OK again to close the Java window. Back on the Preferences window on the Advanced tab, check Enable Java and click OK.
Now close Opera and restart Opera. At this point you should have Java 1.6 support in Opera 9.
To confirm that it works properly I have tested this on the following sites:
http://www.time.gov — select a time zone and a clock applet should appear at the top
http://www.flyordie.com — various online multiplayer games including Reversi and 3D Pool
http://www.logmein.com — Java based remote access client for accessing Windows and Mac OSX desktops